Load sharing in DP applications

Over the past year, classification societies have focused on hidden shortcomings in DP-applications, including cases of no alarm when analogue load share lines have been affected by wire breaks or short circuits.

Ship owners and companies report that classification societies are reluctant to grant approvals for DP systems, knowing that fault consequences such as these can be critical: you risk losing load share ability and ultimately overload, tripping, and even blackout events.
To counter the problem and secure classification approvals, DEIF has developed a CANshare with supervision (option G9) as part of our software v3.06.0 release for the Paralleling and Protection Unit – PPU-3.

With CANshare supervision active (default) each unit’s CANbus ID is set, just as each unit is told which CANshare section it is part of. The latter can be fixed or controlled from M-logic/serial comms., typically based on the BTB position.

A typical DP2 application would handle load share sections like this:

1. BTB open

Here the system consists of two load share sections.

DG1 and DG2: Set to LS section 1
DG3 and DG4: Set to LS section 2

2. BTB closed

The system consists of one load share section.
DG1, DG2, DG3 and DG4: Set to LS section 1

In this case the BTB feedback is wired to ID 2. The BTB position is shared on the CANbus with the other units and can be used in M-logic to switch between LS sections. Alternatively the LS sections can be controlled with Modbus.

Emulation Solution

The new CANshare feature has enabled us to also integrate the Emulation Solution that we successfully introduced with the PPM-3 earlier this year. The emulation mode is activated in a jump menu.

CANshare (option G9) features:

CANshare with supervision of up to 32 DGs

BTB pos. feedback and supervision of up to four BTBs

Handling of up to five load share sections

Active and reactive load share supervision

Dead bus closing with first-up discrimination

Emulation mode for easy test and verification of application functionality